The present invention relates to dental models used in dental articulators, more particularly, it relates to a structure supporting the dental model in the articulator and a method for forming and supporting the dental model.
To accurately form and position false teeth or caps, a dentist normally makes a negative impression of the affected tooth or teeth. The negative impression may be partial, unilateral or bilateral, depending upon the extent of work to be done; the negative impression serves as a mold for developing a die of the patient""s tooth or teeth. The negative impression is obtained by partially filling a tray with thermoplastic material. The filled tray is inserted within the patient""s mouth such that the teeth and adjacent gum sink into and create a cavity within the thermoplastic material. Shortly thereafter, the thermoplastic material will cure and retain an exact impression of the patient""s teeth and adjacent gum. This is an essentially standard technique presently used by most dentists.
To form a tooth die, a pourable casting stone, known as pink stone is poured into the negative impression up to at least the margin or base of the tooth. The pink stone is compacted to preclude voids and remove any air bubbles. After the pink stone is at least partially cured, wax or similar lubricant is swathed upon the surface of the pink stone.
In the prior art, the base for the dental mold is made by one of two methods. First, additional pourable hardenable stone, generally referred to as yellow stone, is poured within the negative impression to cover the pink stone and the retainer with sufficient depth of yellow stone to form a solid base. After both the pink stone and the yellow stone have hardened, the tray and supported thermoplastic material is peeled away to leave a conventional dental model. Alternatively, a patty of yellow stone is formed upon a glass or other smooth surface. The partially or completely cured pink stone is placed thereupon.
In either method, pins are lodged or fixated in the pink stone to extend into and slidably engage the yellow stone. Usually, three pins per model tooth to be worked on are used. The pins serve the function of maintaining registration of the model tooth with respect to the remaining die.
Either of the above processes for making the bases of dental models tends to result in each base being somewhat unique and individualized. When the dental models are placed upon a dental articulator to perform work on the dental model, a substantial amount of time and expertise is necessary to properly attach and align the upper and lower co-acting dental models to reproduce the relationship of the patient""s jaws. The requisite time for aligning the dental models is exacerbated by the non-uniformity of the dental model base configurations and thicknesses and requires yet further time and effort to positionally orient and attach each base upon its respective arm of the articulator.
The dental base described and illustrated in U.S. Pat. No. 4,378,929 is formed by pouring the yellow stone into a mold. The mold standardizes the width, breath, height and configuration of the base. Such standardization permits the use of indexing means in the bases to mount opposing bases of a dental model upon an articulator. Additionally, there is described and illustrated the use of an overhang for forcing a depression in the surface of the base to which the tooth die is attached, which depression delineates a platform. The tooth die (pink stone) is attached upon the platform. To sever a model tooth from the tooth die, mesial and distal saw cuts are made through the tooth die to a point just below the line of demarcation between the tooth die and the base. The line of demarcation is coincident with the surface of the platform. As the saw blade need not be angled to have the saw end clear the opposing quadrant of the tooth die, the depth of cut into the base may be minimized at a point just below the platform surface.
In U.S. Pat. No. 4,382,787, there is described an articulator attachable to opposed pairs of dental model bases through a mounting means. The articulator is particularly easily usable with size standardized bases for dental models of the type described in U.S. Pat. No. 4,378,929. One embodiment of the mounting means usable as part of the articulator includes a tab, tang or ridge for penetrable engagement with a slot formed in the rear sidewall of a dental model base.
U.S. Pat. No. 4,842,242 discloses a standard sized base for a full or quadrant dental model and having a slot formed in the rear sidewall of the base, which slot is enhanced for adhesive engagement with an arm of an articulator.
It is an object of the present invention to provide a dental model having a base immovably supporting the dental model in a dental articulator.
It is another object of the present invention to provide a supporting plate for supporting the dental model with the provided base in a dental articulator.
It is a further object of the present invention to provide means for aligning the supporting plate of the articulator with the dental model having the provided base.
The invention provides a supporting structure for supporting a dental model in a dental articulator. The supporting structure includes an articulator plate and a base of the dental model. The base of the dental model is provided with at least one cavity extending internally into the base from its bottom surface. The shape of the cavity is determined by the mold forming the base. In one embodiment, the cavity has straight walls. In another embodiment, the cavity is barrel-shaped. The articulator plate is provided with an alignment structure, which may include a pair of straight-walled projections, for use in combination with the straight-walled cavity, or a pair of curved springs, for use in combination with barrel-shaped cavity. The articulator plate is secured to the base by inserting and retaining the alignment structure inside the provided cavities. The articulator plate is provided with a shaft for attaching the dental model to a dental articulator.
The above and other objects, aspects, features and advantages of the invention will be more readily apparent from the description of the preferred embodiments thereof taken in conjunction with the accompanying drawings and appended claims.